JP2661497B2 - Strip crown control device and strip crown control method during hot rolling - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a sheet crown in hot rolling in which a sheet crown control amount is corrected during rolling.

[0002]

2. Description of the Related Art In the rolling of a sheet material, in order to control the crown amount of a rolled sheet within a target range, there have conventionally been used techniques such as a six high mill, a pair cross mill, a double chock bender and a work roll shift device. Has been taken. For example, Japanese Patent Application Laid-Open No. 55-126310 discloses that in such a crown control, the detected value of the sheet crown on the exit side of the final stand is fed back to the roll bender device so as to eliminate the difference between the detected sheet crown and the target sheet crown. A method for controlling a roll crown device and controlling a sheet crown is disclosed. Also, JP-A-61-9
No. 914 discloses a crown which calculates a sheet crown amount from an edge part thickness and a center part sheet width corrected by a sheet width direction movement amount, a sheet width deviation, and a sheet profile, and performs roll bending control based on this value. A control method is disclosed.

[0003] However, in these feedback control methods, for a portion to be rolled from the first measurement of the sheet crown to the start of the control, no correction is made to the deviation from the target value of the sheet crown. There is a problem that it is not applied.

On the other hand, Japanese Patent Laid-Open No. Sho 60-54216 discloses that
A rolling control method for estimating and calculating a shape deviation or a sheet crown deviation on the exit side of a stand based on a deviation of a rolling load or a deviation of a work roll crown amount, and controlling a bending force of the stand has been proposed. Also, JP-A-3-28
Japanese Patent No. 5707 proposes a sheet crown control method in which a control amount of a crown control mechanism is corrected during rolling according to a deviation amount of a sheet crown from a target value caused by a difference between a predicted value and an actual measurement value of a rolling temperature. ing.

However, in the control method proposed in Japanese Patent Application Laid-Open No. Sho 60-54216, since rolling conditions other than the rolling load and the work roll crown amount are not taken into consideration, it is difficult to perform sufficient control. Further, in the control method proposed in Japanese Patent Application Laid-Open No. 3-285707, when calculating the crown deviation caused by the rolling temperature, the temperature distribution in the sheet width direction is determined, for example.

T = T ₀ −ax ² (1) where T: temperature at each position in the sheet width direction T ₀ : temperature at the center of the sheet width a: coefficient x: distance from the center of the sheet width Are estimated based on simple test formulas. However, FIG.
As shown in the figure, in the actual operation, the estimated value of the temperature distribution in the sheet width direction does not match the actual value, so the control amount of the crown control mechanism is set appropriately due to the error of the estimated value with respect to the actual value. It becomes impossible to do. Moreover, there is a problem that the plate crown cannot be sufficiently controlled only with the parameters considered here.

[0006] In particular, the actual value has not been taken into account as information relating to the sheet crown on the finishing side, so that if the predicted value of the sheet crown on the finishing side deviates from the actual value, the final sheet crown will change. There was a problem that it deviated significantly from the target value. FIG. 6 is a graph showing this, and shows that when the actual value of the coarse bar crown deviates from the predicted value, the crown on the finishing side greatly fluctuates.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to obtain a sheet crown from a target value due to a difference between a predicted value and an actual value of a rolling temperature. The amount of deviation and the amount of deviation of the sheet crown caused by the difference between the predicted value and the actual value of the sheet crown on the finishing entry side are reduced,
An object of the present invention is to improve sheet crown accuracy over the entire length of a rolled material at low cost.

[0008]

In order to achieve the above object, the present invention provides a sheet crown control apparatus for hot rolling of a rolled material, comprising: an inlet-side sheet crown used for setting a crown control amount of a crown control mechanism. Means for determining a deviation amount from a target value of the sheet crown caused by a deviation between the predicted value and the actual value of the sheet crown, a means for obtaining a temperature distribution in the sheet width direction on the entry side of the rolled material, the deviation amount and the sheet width Means for correcting the crown control amount during rolling according to the directional temperature distribution.

In this case, the exit side width direction thermometer installed on the exit side of the final stand, and the deviation between the actual value and the predicted value obtained by the exit side width direction thermometer are transferred to the stand at least two steps behind the final stand. Means for feeding back and modifying the control amount of the crown control mechanism may be further provided.

Further, in the present invention, a method for controlling a sheet crown in hot rolling of a sheet material includes a method for controlling a sheet crown caused by a deviation between a predicted value and an actual value of an entrance-side sheet crown used for setting a crown control amount of a crown control mechanism. A step of obtaining a deviation amount from a target value of, a step of obtaining a temperature distribution in the sheet width direction on the entry side of the rolled material, and rolling the crown control amount in accordance with the deviation amount and the temperature distribution in the sheet width direction. And a correcting step inside.

Further, an output side width direction thermometer is installed on the output side of the final stand, and the deviation between the actual value and the predicted value by the output side width direction thermometer is fed back to the stand at least two steps from the final stand. Thus, the control amount of the crown control mechanism may be corrected.

[0012]

According to the present invention, the difference between the predicted value and the actual value of the entrance-side sheet crown used for setting the crown control amount of the crown control mechanism from the target value of the sheet crown and the rolling material of the rolled material. The crown control amount is modified during rolling according to the temperature distribution in the width direction on the entry side.

Further, the deviation between the actual value and the predicted value obtained by the exit side width direction thermometer is fed back to the stand at least two steps behind the final stand on the exit side of the final stand,
The control amount of the crown control mechanism is modified.

[0014]

An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a view showing the concept of the present invention, and FIG. 2 is a flowchart showing a procedure for correcting a crown control amount of a crown control mechanism in the present invention.
As shown in FIG. 1, in the present invention, a rolled material rough bar profile meter 2 to the inlet side of one and the entry side widthwise thermometer 3 ₁ installed, if necessary, the final stand delivery side of the exit side placing the exit side widthwise thermometer 3 ₂ for measuring the width direction temperature distribution. In order to correct the control amount of the crown control mechanism F such as a work roll bender or a CVC roll, the actual value _Cθact of the _incoming coarse bar crown is measured by the coarse bar profile meter 2 (step 11 in FIG. 2). Next, the actual value C _θact of the coarse bar crown on the entry side and its predicted value C _θcal
Is calculated (step 12).

[0015] In parallel with this, to measure the width direction temperature distribution obtained by the inlet side widthwise thermometer 3 ₁ (Step 1
3) The width direction distribution of the deformation resistance at the plate edge of the rolled material 1 is obtained from the obtained actual value of the width direction temperature distribution on the entry side (step 14).

On the basis of the deviation ΔC _θ calculated in step 12, the rolling load is applied while taking into account the widthwise distribution of the deformation resistance obtained in step 14 (step 15 shows this state). In consideration of the distribution, the correction amount of the control amount of each stand actuator is calculated so that the crown ratio becomes constant (step 16).
The correction amount calculated in this way is set for each stand actuator (step 17), whereby the rolled material 1 is obtained.
Can be implemented over the entire length of the control.

As described above, as information on the strip crown on the finishing entry side of the rolled material 1, the deviation between the actual value and the predicted value of the coarse bar crown, and the actual value and the predicted value of the width direction temperature on the entry side. Is obtained, and the feed crown is dynamically fed forward to each stand actuator, whereby the strip crown at each stand can be made constant over the entire length of the rolled material 1.

[0018] If necessary, further obtains the measured value of the width direction temperature distribution of the outlet side by installing the outlet side widthwise thermometer 3 ₂ to a final stand delivery side, the strip crown from the deviation between the predicted value and the measured value The amount of deviation may be calculated to correct the control amount of the stand actuator at least two steps after the last stand. In this way, if an error has occurred on the output side of the final stand, the error is fed back to the stands at least two steps behind the final stand as a sheet crown deviation, and the error of the sheet crown on the output side is minimized. Can be limited.

In the method for correcting the crown of the plate in the above embodiment,

[Number 2] ^{_{C R = C R CAL + △}} C R (2) provided that, _{C R:} strip crown C _R ^CAL: Crown estimate by the conventional strip crown estimation model △ _{C R:} the expression amount of correction of entry side crown Is used. Correction amount △ C _R is obtained by adding a function of the deviation and the load distribution in the plate width direction temperature deviation between the predicted and measured values of the entry side crown, it can be obtained beforehand by theoretical analysis . Hereinafter, this will be described.

The crown estimation value C _R ^CAL can be ^{calculated as} described in a special report “Theory and Practice of Sheet Rolling” edited by the Iron and Steel Institute of Japan (September 1, 1984, page 102).
Typically,

Equation 3] ^{_{C R CAL = α P · P}} -α C · R CW - {α C + (B / L 2) 2} · R CB -α B · J + η · C RO (3) However, P: rolling Load B: Plate width R _CW : Work roll crown R _CB : Backup roll crown J: Roll bending force L ₂ : Roll barrel length C _RO : Inlet side plate crown α _P : Work roll axis deflection influence coefficient α _C due to rolling load: roll crown work roll axis deflection influence coefficient alpha _{B by:} heart work roll axis by the roll bending force deflection influence coefficient eta: represented by entry side crown genetic factor. First, considering the deviation ΔC _θ of the entrance side plate crown (rough bar profile),

△ C _θ = C _θcal −C _θact (4) where C _θcal : calculated value of coarse bar crown C _θact : obtained by actual value of coarse bar crown The deviation obtained in this way dynamically corrects the entry side plate crown C _RO in equation (3). That is,

By setting △ C _R = η △ C _θ + C _T (5), it is possible to correct the rough bar profile actual value.

[0021] Section C _T of formula (5) is a term accounts for the actual value of the inlet side width direction temperature distribution will be described below that calculated. The effect of the temperature difference appears as a difference in deformation resistance as shown in FIG. When the deformation resistance changes in the width direction, the sheet crown can be corrected in consideration of the influence of the temperature difference by considering the distribution of the rolling load P. As described above, conventionally, the temperature distribution in the width direction is empirically expressed by Expression (1), and the predicted value is used as the temperature T at each position in the plate width direction. In many cases. Therefore, in the embodiment of the present invention, the actual value T _act of the temperature distribution in the width direction is obtained. The difference ΔT between this and the predicted value T is

６T = T−T _act (6) This ΔT affects the deformation resistance (load) distribution.

The deformation resistance value k _fm is generally

(Equation 7) Therefore, the deformation resistance difference Δk _fm for ΔT is

(Equation 8) Becomes Further, using the deformation resistance, the rolling load P becomes

P = k _fm {R ′ (h ₁ −h ₂ )} ^1/2 · Q _P (9) where R ′: roll flat radius h ₁ , h ₂ : between the entrance side and the exit side, respectively. Plate thickness Q _P : expressed by rolling force function Using this, the rolling load difference ΔP is

ＰP = △ k _fm ｛R ′ (h ₁ −h ₂ )｝ ^1/2 · Q _P (10) That is, the influence of the temperature difference in the temperature distribution in the plate width direction can be expressed as a load distribution difference by using the above equations (6) to (10). Thus, the _{C T} in the formula (5)

Since C _T = α _P · △ P (11), equation (5) is

ＣC _R = η △ C _θ + α _P · △ P (12)

[0023] Thus using the obtained △ C _R as the correction amount of crown control, and modify the control amount of each of the stand actuators as crown ratio is kept constant, the coarse bar crown and the inlet side widthwise temperature distribution The effect is corrected at each stand (the above control is referred to as “control 1”).

[0024] If necessary, determine the delivery side widthwise temperature distribution in the final stand delivery side established a widthwise thermometer 3 _2, delivery side widthwise temperature distribution using the above equation (6) - (11) The deviation between the actual value and the predicted value is converted into a crown amount, which is fed back to the actuators of the stands up to at least two stages to correct the control amount (this control is referred to as “control 2”). Is also good.

FIG. 4 is a graph showing the effect of the embodiment of the present invention described above in comparison with the conventional example. A shows the relationship between the plate crown and the distance from the tip of the coil when both control 1 and control 2 are performed. From this graph, conventionally, the plate crown fluctuated up to about 40 μm,
By performing the control 1, the fluctuation of the plate crown becomes 20
It can be understood that the fluctuation of the sheet crown can be suppressed to 10 μm or less by performing the control 1 and the control 2. Note that the dotted line in FIG. 4 indicates a predicted value of the plate crown.

[0026]

As is apparent from the above description of the present invention in detail with reference to the embodiments, the present invention provides a target value of a sheet crown target value resulting from a deviation between the actual value and the predicted value of the entrance side sheet crown. , And the deviation amount of the sheet crown caused by the deviation between the actual value and the predicted value of the rolling temperature can be reduced, and the accuracy of the sheet crown over the entire length of the rolled material can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the concept of the present invention.

FIG. 2 is a flowchart showing a procedure for correcting a crown control amount in the present invention.

FIG. 3 is a graph showing an influence of a width direction temperature distribution on a deformation resistance.

FIG. 4 is a graph showing the effect of the embodiment of the present invention in comparison with a conventional example.

FIG. 5 is a graph showing that the actual value of the temperature distribution in the sheet width direction does not match the predicted value in the conventional sheet crown control method.

FIG. 6 is a graph showing how the deviation between the actual value and the predicted value of the entrance-side sheet crown affects the exit-side sheet crown in the conventional sheet crown control method.

[Explanation of symbols]

1: rolled material, 2: crude bar profile meter, _{3 1:} inlet side widthwise thermometer, _{3 2:} delivery side widthwise thermometer, F: crown control mechanism

Claims (4)

(57) [Claims] 1. A sheet crown control apparatus for hot rolling of a rolled material, comprising: a sheet crown caused by a deviation between a predicted value and an actual value of an input side sheet crown used for setting a crown control amount of a crown control mechanism. Means for determining a deviation amount from a target value; means for determining a sheet width direction temperature distribution on the entry side of the rolled material; and, in accordance with the deviation amount and the sheet width direction temperature distribution, rolling the crown control amount. Means for correcting the thickness of the sheet crown. 2. The strip crown control device according to claim 1, wherein the outlet side width direction thermometer installed on the outlet side of the final stand, and a deviation between the actual value and the predicted value by the outlet side width direction thermometer. Means for feeding back to the stands at least two steps from the last stand to correct the control amount of the crown control mechanism. 3. A method for controlling a sheet crown in hot rolling of a rolled material, the method comprising the steps of: setting a crown control amount of a crown control mechanism; A step of obtaining a deviation amount from a target value, a step of obtaining a temperature distribution in the sheet width direction on the entry side of the rolled material, and rolling the crown control amount according to the deviation amount and the temperature distribution in the sheet width direction. A crown correction method, comprising the steps of: 4. The strip crown control method according to claim 1, further comprising an outlet width direction thermometer installed on the outlet side of the final stand, wherein a difference between the actual value and the predicted value by the outlet width direction thermometer is provided. A method according to claim 1, wherein the deviation is fed back to a stand at least two steps behind the last stand to correct the control amount of the crown control mechanism.